feat: refactoring and cleanup

src/Form/Service/Abstract/AbstractParticipantFieldHandler.php

@@ -182,4 +182,33 @@ abstract class AbstractParticipantFieldHandler implements ParticipantFieldHandle
     {
         return [];
     }
+
+    /**
+     * Finds an item by ID from an array of objects.
+     *
+     * Generic helper for validating a selected ID against an array of available
+     * items and returning the matching object. Used by handlers that need to
+     * validate service, pickup, or other selections against available options.
+     *
+     * @param mixed    $selectedId The submitted ID to find (string or int)
+     * @param object[] $items      Array of objects with an `id` property
+     *
+     * @return object|null The matching item, or null if not found or invalid ID
+     */
+    protected function findItemById(mixed $selectedId, array $items): ?object
+    {
+        if (null === $selectedId || (false === is_string($selectedId) && false === is_int($selectedId))) {
+            return null;
+        }
+
+        $id = (int) $selectedId;
+
+        foreach ($items as $item) {
+            if ($item->id === $id) {
+                return $item;
+            }
+        }
+
+        return null;
+    }
 }